Update Vaccine Terms to include ICD Codes

[aljones15]

The WHO has an existing API endpoint that uses ICD-11 Codes to classify vaccines for certain conditions.

ICD API

ICD Vaccine documentation

ICD Api github examples

One more win we get by using ICD-11: the entire api already returns RDF or JSON-LD. See Content Negotiation for the format.

So the context here should at the minimum add a new term for ICD-11-Code and ICD-11-URI.
Additional suggestions for new terms to add to the context include older version of ICD:

• ICD-10-Code
• ICD-9-CM

[msporny]

Agree that we should look into this.

[tplooker]

Related to #20 and #18

[aljones15]

One additional note here: support needs to be ICD-9 and up in order to support U.S. Vaccine standards.